Various data are stored in a storage device. Such data includes, for example, information to be confidential (confidential information) for persons other than some persons. Some storage devices include a function of restricting access to such confidential information. More specifically, for example, in a storage device that is configured to be able to set with a password, it is possible for only a user inputting the password to access the confidential information. In addition, PTL 1 discloses a system that restricts a function of handling confidential information stored in a memory or a hard disk of a personal computer, on the basis of, for example, a distance from the personal computer to a wireless key.